Supreme has started using Lord adhesives to bond composite and metal components on their range of customized vehicle bodies.
“We continually look for ways to improve the appearance and performance of our products,” said Kelvin Wittmer, Design Engineer at Supreme. “But unsightly rivets made our products look less professional. Knowing our product is superior, we sought a method to make our bodies look more consistent with the OEM chassis.”
Supreme decided to partner with Lord Corporation and Composites One to develop and validate a specialty structural adhesive that would eliminate unsightly screws on their products.
“Supreme was extremely concerned with how switching to adhesives would affect their reputation,” said Dan Bradshaw, a Senior Account Manager for Lord Corporation. “They were to be the first major manufacturer of their kind to remove screws from storage compartment doors and they wanted to eliminate the possibility of failures. Because Supreme had long-term success with their current methods, concerns of switching included the possibility of door panels popping from the frames or the door jambs coming loose from the sidewall. Supreme also was sceptical as to whether or not Lord could truly build a better unit in less time.”
The initial experiments in 2001 involved door panels and jambs on the truck body panels of the Spartan line. The doors were an ideal trial because structural bonding could be evaluated without modifying the box structure itself. Further, the screws used were located every four- to six-inches and removing them would immediately improve the appearance, as well as offer the added benefit of eliminating potential corrosion around the screws. Lord 7545A/B, a structural urethane adhesive with a great track-record in bonding fibreglass to painted metal in the marine and automotive industries, and Lord 606/6GB, an acrylic adhesive developed specifically for bonding unprepared metal to fibreglass, were selected.
Supreme conducted extensive testing in order to validate the strength of their bonded designs including mock-ups and sample panels. A full battery of automotive exterior body panel tests were completed to ensure the bond would hold for the life of the body, including accelerated aging test cycles.
Structural bonding has now been integrated into six of the Supreme production plants. The most recent adhesive bonding application includes roof rails and sidewalls where rivets were eliminated. The bonding processes will be rolled out to the other Supreme manufacturing locations throughout 2006.
In addition to improved appearance, Wittmer credits the adhesives as saving time in the production process. “Before switching to adhesives,” said Wittmer, “we had to take an extrusion to a punch, put it up, drill it, stick the fasteners in and clamp it and fasten from the inside. Now we simply shoot a bead of adhesive and push the panels together. Not only is the end-result stronger, it probably saves us several hours for every unit.”
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